6 year old with high fever (102.7) and severe headache - no other symptoms. What could be cause? ER or wait 5 hours for Dr.?

Fever/headache. This could mean many possible causes. It may be a virus or a more serious illness. Treat his fever and have him assessed in the ER. If they feel he is sick, he will be seen immediately. All the best.
Fever headache. So sorry to here your child is ill. If he appears very ill do not wait for the clinic to open go to the emergency room. If he is ill but still seems ok then you can wait to be seen in a clinic . I hope he gets better soon .